Electrically heated device



- Had.

April 12,1949. G. VAN DAAM 2,467,349

' ELECTRICALLY HEATED DEVICE Filed Aug. 13, 1943 3. Sheets-Sheet 1 15! 4 Geek/r149 044M MZJw/lc a a INVENTDR BY \y 3 TToRNsws April 12, 1949. e. VAN DAAM 2,467,349

ELECTRICALLY HEATED DEVICE Filed Aug. 13, 1943 3 Sheeis-Sheet 2 GERPIVT' MID/MM INVENTOR BYQAMAM ATTORNEYS April 1949- e. VAN DAAM 2,467,349

ELECTRICALLY HEATED DEVICE Filed Aug. 13, 1945 3 Sheets-Sheet 3 F76. 6. f f 40 l I 4/ I ff i a; I

67 1 I I l I I Fla. 8. (f?

I n 10; I, 106" E 107 1 g JkaJIJZI/ci GEEK/7' VAN 0419 R my! mve r To 81 JMZJw/M 14 7% ATTORNEYS:

, pads, and the like.

size of the mattress.

Patented Apr.;12, 1949 UNITED STATES PATENT OFFICE ELECTRICALLY HEATED DEVICE Gerrit Van Daam, Buffalo, N. Y. Application August 13, 1943, Serial No. 498,460

. 6 Claims. 1

, This invention relates to electrically heated de vices and methods of making them, and more particularly to electrically heated mattresses, The principal object of the invention is to provide new and improved devices of these types and new and improved methods of making them.

In the drawings accompanyin this specifica- -tion, andforming apart of this application, there are shown, for purposes of illustration, several forms which the invention may assume, and in these drawings:

I Figure '1 is a plan view, diagrammatic in part, of an electric heater grid, along with electric circuit control means therefor, particularly adapted for embodiment in a mattress,

Figure 2 is a plan view, on a scale smaller than Figure 1, of a mattress, in outline, which may embody a heater grid similar to that shown in Figure 1, Figure 2 showing, diagrammatically, electric control means of diiferent embodiment,

Figure 3 is a longitudinal section of a mattress embodying the invention,

Figure 4 is a plan view of another embodiment of the invention,

Figure 5 is a section taken on the line 5-5 of Figure 4,

Figure 6 is a fragmentary enlarged view of section-showing a step in a method of making an electrically heated device in accordance with the invention,

Figure 7 is a fragmentary enlarged view in section, showing another step in a method of making an electrically heated device in accordance with the invention, and

Figure 8 is an electrical diagram of another embodiment of the invention.

Referring first to Figure 1, this shows, partly diagrammatically, a unitary woven electric heater grid which, if it is to be embodied in a mattress, has an area commensurate with the upper surface of the mattress. A convenient actual size of the grid is approximately five and one-half feet long and somewhat less than three feet wide, but the grid may be larger or smallerv depending on the The heater grid as here shown includes a transverse intermediate portion Ill, and portions I l, 12 adjacent the intermediate portion Ill, and also end portions I3, H at the ends of the portions ll, [2 respectvely. The grid as here shown includes warp elements Hill and l5b in .the selvedge and a desired plurality of intermediate warp elements Hi all of electrical insulat; ing. yarn, preferably of glass fibre, extending the entire length of the weave. The portions l0, I3,

and I4, include weft elements 20 of electrical insulating yarn, preferably of glass fibre, interwoven with the warp elements l5a, I6, and 15b. The warp elements l6 are shown as spaced laterally from each other and from the warp elements l5a, l5b, this spacing being any desired, suitable amount. The warp elements l6 are here shown as each comprising two individual strands of yarn, and the warp elements I5a and l5b are here shown as comprising five individual strands of yarn, but in either case any desired, suitable number of strands may be used.

The portions l I, I2 include weft elements l1, l8 interwoven with the warp elements l5a, l6, and l5b. The weft elements I1, l8 are shown in black merely for the purpose of making them stand out so as to be readily traceable. The weft elements l1, l8 each comprise electric resistance wire. By wire is meant either stranded wire, or solid, round section wire, or any suitable form of resistance conductor adapted for weaving. Each wire is preferably primarily coated with an insulating covering, preferably of glass fibre, which may be subsequently coated with rubber as hereinbefore set forth. The weft elements appear more or less diagrammatically in section in Figure 6 and there are shown as comprising a wire covered with glass fibre in turn covered with rubber. The weft elements l1, l8 are preferably of different electrical resistance and are here shown as electrically connected at 25 to a common lead conductor 26a. From the point 25 the weft elements l1, l8 are laterally spaced from each other longitudinally with respect to the length of the weave any desired suitable distance, and run collaterally back and forth and are interwoven with the warp elements l5a, l6, and l5b until they reach the intermediate portion IO. Here the weft element l8 extends, as the portion l8a, longitudinally of the weave at the margin of the left hand selvedge of the portion l0, and the weft element l1 extends, as the portion [1a, longitudinally of the weave at the right hand selvedge of the portion Ill. The portions Fla and Illa merge with the weft elements l1, 18 in the portion [2 and in that portion they run collaterally and are interwoven with the warp elements l5a, I 6, and I5!) as in the portion l l. The terminal ends I11 and l 81, of the weft elements l1, l8 are carried out of the weave adjacent to the portion H or, if desired, may be longitudinally interwoven with one or more of the weft elements 20 of the portion I 4.

The longitudinal extent of the portion I2 is here shown as about one-half of that of the portion II, but other proportions may be used. The

longitudinal width 01 the portions I0, I3, and I4 need not in an actual grid be as large a percentage of the total length of the grid as shown in Figure 1.

The lead conductor 28a, though it may be and preferably is disposed on top of the left hand selvedge is here shown as disposed along the edge of the selvedge for the sake of clearness. The lead conductor 28a is here shown as merging with a portion 26b carried over and on top of the por-' tion Ill and leading to and electrically connected to a contact 21 of a thermoresponsive cut-out 28 which desirably has a casing as indicated by the dotted rectangle. The thermoresponsive cut-out 28 has a movable contact 29 to which is electrically connected a lead conductor 280 which extends from the contact 29, on top of the portion Ill transverselyoutwardly, then longitudinally along the left hand selvedge, then transversely along the portion I4 where it may be interwoven with the warp elements I51; and IS. The conductor 28c as well as the terminals I1t, I8t of the weft elements I1, I8 may be carried out of the weave in any desired, suitable way and the conductor 28c and terminals I1t, I8t are electrically connected to the respective prongs of a plug 30.

The portion of the lead conductor 26c running along the left hand selvedge is shown separated from the selvedge for the sake of clearness, but this portion as well as the lead conductor 26a may be and preferably is disposed on top of the selvedge. In any event, before the grid shown in Figure 1 is embedded in rubber or the like, as hereinafter described, it is preferred but not essential to hold the lead conductors in place along the selvedge with insulating yarn (notshown) looped in any suitable way about the selvedge and the lead conductors.

It will be understood that the lead conductors 28a, 28b, 260 are preferably of relatively high conductivity and heavier than the wire in the weft elements I1, I8. The terminal portions I1t, I8t preferably are connected to such lead conductors leading to the plug 30.

The plug 30 is cooperable with a socket 3| 'to which are connected conductors 32, 33, 34 in turn connected to respective terminals of a switch 35 which is a so-called 3-heat switch various kinds of which are well known to those skilled in the art. The switch 35 has terminals connectable to line conductors 36, 31. The 3-heat switch 35 is of any suitable type whereby the line conductors 36, 31 may be electrically connected so that the weft element I1 only is fed with current, or the weft element I8 only is fed with current, or both the weft elements I1, I8 are fed with current. It will be evident that especially if electromotive force of but one magnitude is available, as from a single pair-of line conductors, it is preferable to make the weft elements I1, l8 of different electric resistance, so that the grid area may be heated to any selected one of a plurality of different maximum temperatures, in this instance, three. If more than one electromotive force is available the weft elements I1, I8 may be made of the same resistance if desired and difierent heats obtained by application of different electromotive forces.

The thermal cut-out 28 is so constructed and arranged that the contacts 21, 29 will be disengaged when a maximum safe temperature is reached.

The grid having been constructed as hereinbefore described in connection with Figure 1, it is dipped or otherwise coated with latex-type material, either natural or synthetic, such as natural or synthetic rubber latex, vulcanizable, or other suitable material. The so-coated grid may then be vulcanized, or it may be laid on a suitable flat surface and a mass of latex-type material applied to the top side, or, instead, a sheet of unvulcanized rubber or rubber-type material placed on the top side. Thisflrst assembly is then placed under pressure, whereby the said mass or sheet as the case may be is impressed into and adheres to the coated grid. This assembly may be then turned over and a mass of latex-type material applied to the upturned side, or, instead, a sheet of unvulcanized rubber or rubber-type material placed on the upturned side. This second assembly is then vulcanized under pressure in a mold. The process may be simplified by disposing the woven grid, coated with latex-type material which preferably but not necessarily has been vulcanized, between two sheets of unvulcanized rubber 48, H, as diagrammatically indicated in Figure 6, then placing this assembly in a mold comprising parts 42, 43 and vulcanizing this assembly under pressure in the mold, to bring the assembly to the form'diagrammatieally indicated in Figure '1. In either of the described methods the woven grid and the embedding rubber become a solid unitary mass or pad 45, the interstices in the woven grid being filled with rubber. The lead conductors 28a, 26b, 260, Ht, I8t are also embedded in the rubber mass. The thermoresponsive means 28 is of course also embedded in the unitary pad by the described methods.

Figure 3 shows a longitudinal section of a mattress 46 in which a pad such as 45 is embodied. The mattress 48 may comprise an upper wall 41, and an under wall 48 generally parallel to the wall 41, and a circumscribing side wall 49. The walls 41, 48, 49 may be made of ticking or other suitable material. The mattress may be fllled with a filling 58 of sisal, hair, moss, or other suitable filling material. The pad 45 is embedded in the filling 50, and the principal thickness of the filling may be below the pad 45. Desirably, a sheet of asbestos 5| or other suitable heat insulating material preferably non-inflammable, desirably of somewhat larger area than the pad 45, is inter-- posed between the under side of. the pad 45 and the filling 50. If desired the pad 45 may be [astened to the sheet 5| with thread or. cord or in any other desired way. If desired, the filling 52 adjacent the upper side of the pad 45 may be made of fibrous non-inflammable material of any suitable kind.

A mattress constructed as hereinbefore described has many advantages among which are safety from short circuits and absence of corrosion of the wires and other conductors; resilience and resultant comfort for the user while at the same time the strains put upon the pad 45 will not result in breakage of the conductors (resistance wire or lead conductors) .nor in relative shifting of the parts of the conductors with respect to each other, nor with respect to the supporting means for the conductors. The pad 45 is highly flexible in all directions without resulting in any undesirable displacement of the parts thereof, and is sufliciently' strong to withstand the great stresses put upon it by the weight of a person lying on the mattress, including the bending and tensile stresses due to the shifting of the person's weight. The pad 45 and the electrical connections thereto are waterproof.

The conductors 28c, l1t, and I8t have been shown in Figures 1 and 3 as separate but they may be twisted together and covered, so as to V thermo-couple 53.

constitute a flexible cable or cord extending from the side wall 49 to any desired suitable length and leading and connected to the plug 30.

Instead of the thermal cut-out 28 interposed in the lead conductor 28a-28c, thermoresponsive means either suitable for mechanical or electrical remotecontrol of switch means may be used. In the illustrated instance shown in Figure 2 a thermocouple 58 is indicated. The thermo-couple 53 has conductors 54, 55 connected to its terminals and leading to a plug 58 cooperable with a socket 5'! connected by conductors 58, 59 to a milliam- "meter, or any other suitable electric current responsive indicating means 80. Desirably the thermo-couple 53 and the conductors 54, 55 are embedded in the mass of rubber which embeds the woven grid. If desired a current amplifier 8| may be interposed in the conductors 58, 59. The indicating means 80 is here shown as provided with a pointer 82 cooperable with a relatively stationary adjustable contact 83. The pointer 82 and contact 83 are interposed in a circuit 10 which includes an operating coil 84 which when energized is adapted to lift a briding contact 85 out of engagement with relatively stationary contacts 88. The circuit I0 is here shown as connected to and feedable from the line wires 15, I6 and the relay contacts 85, 89 as interposed in the line wire IS. The line wires I5, I8 are connected to a 3-heat switch 11 in turn connected to a socket 3| connectable to the plug 30 which may be electrically connected to the resistance wires as in Figure 1. If the thermal cut-out 28 is omitted, the lead conductor 29a,

28b, 280 of course does not need to extend into the portion I0 but may be continuous along the selvedge from the point to the portion I4, to the plug 30.

The embodimentlof Figure 2 is particularly advantageous in treating hospital patients where a particular temperature at the surface 41 of the mattress is desired. The apparatus may be calibrated to determine what temperature at the surface will result from a given temperature at the For example, the temperature at the thermo-couple may be at, say, 140 F. which in a particular embodiment will result in a maximum temperature of 115 F. at the surface of the mattress after stable heat dissipating conditions have been reached. The dial of the instrument 80 may be calibrated to read in degrees of, mattress surface temperature in a range from the lowest to the highest temperature, and the contact 83 adjusted to a selected desired temperature. Naturally the maximum surface temperature will be determined by the maximum safe temperature at the thermo-couple 53.

Referring to the embodiment shown in Figure 8, the dot-and-dash line 80 indicates the outline of a unitary woven electric heater grid which may be embedded in rubber as hereinbefore described. The unitary grid of Figure 8 has weft elements comprising electric resistance wire-8I, 82 which run collaterally back and forth across the weave in the same manner as the weft elements I1, I8 of Figure 1 but the weft elements 8|, 82 cover only the portion of the weave from an end portion 83 to an intermediate portion 84 (corresponding respectively to the end portion I3 and the intermediate portion I0 of Figural). The weft elements 8|, 82 have ends electrically connected to a common lead conductor 85, the other ends adjacent the intermediate portion 84 being connected to lead conductors 88, 81.

The unitary grid 80 also includes weft elements .atures, in this instance three.

comprising electric resistance wire 9|, 82 having ends adjacent the intermediate portion 84 electrically connected to a common lead conductor 93. The weft elements 9|, 92 cover the area between the intermediate portion 84 and anend portion 94 (corresponding to the end portion I4 of Figure 1) and at the end portion 94 are connected to lead conductors 95, 98 respectively.

The lead conductors 88, 93 are here shown as connected to a contact 91 of a thermal cut-out. The other contact, 98, of the thermal cut-out is connected to a common lead conductor 99. The lead conductors 88, 81, 95, 98, '99 may be conveniently brought out so as to form a cable the conductors of which are connected to the respective prongs of a 5-prong plug I00. The prongs of the plug I00 are respectively cooperable with the holes of a 5-hole socket IOI. Conductors I82, I03 leading from the socket IOI are connected to two terminals respectively of a 3-heat switch switch I08, another terminal of the switch I08 being connected by a jumper I09 to the line I05. The remaining conductor, IIO, from the socket IN is here shown as electrically common with the other line conductor I05a. Thus the socket IM and plug I 00 are so constructed and arranged that conductors IIO, I06, I01, I02, I03 are connectable to lead conductors 99, 95, 96, 86, and 91 respectively.

It will be evident that when the contacts 91, 98 are in engagement, the common lead conductor 99 is adapted to feed into either the conductor or the conductor 93 or both. The 3-heat switch I04 may be turned so that only the weft element 8| is fed with current, or only the weft element 82, or both of these weft elements, thereby heating the portion between the intermediate portion 84 and the end portion 83 to any selected one of a plurallity of different maximum temperatures, in this instance three. In like manner the 3-heat switch I08 may be turned so that only the weft element 9I is fed with current, or only the weft element 92, or both of these weft elements, thereby heating the portion between the end portion 94 and the intermediate portion 84 to any selected one of a plurality of different maximum temper- It will of course be evident that either of the switches I04, I08 may be in the off position while the other is in any selected on" position, or both may be in any selected on position. The embodiment of Figure 8 enables heating only mainly the trunk of the body of a patient, or only mainly the legs and feet of the patient, or heating both trunk and legs and feet but at different temperatures, or heating both trunk and legs and feet at the same temperature.

It will be evident that insteadpf the thermal .cut-out 9I-98, a thermally responsive device the .grid of Figure 1 but in which there is but one weft element comprising an electric resistance wire H6. A lead conductor H1 is connected to one end of the wire H8 and a lead con ductor H8 is connected to the other end of the wire H6. The lead conductors H1, H8 may be brought out through and molded in a rubber extension H9 integral with the rubber mass I20 in which the woven heater grid is embedded. The lead conductors 26, Ht, l8t of Figures 1, 2, and 3 and the lead conductors 99, 95, 96, 86, 81 of Figure 8 may be similarly brought out from the respective grids in a rubber extension integral with the mass of rubber embedding the grid, similarly to the extension H9 and mass I20.

An embedded thermal out-out III is here shown as interposed in the lead conductor Ill but may be interposed at any other desired posi-'- tion in the circuit.

Heating devices in accordance with the invention, particularly the simpler forms as in Figures 4 and .5, may be used as heated mats, as in front of hotel doorways, etc., or for policemen to stand on, or under fabric rugs or mats, or encased in skilled'in the art that each of the illustrated em bodiments of the invention provides a new and improved electrically heated device and accordingly, each accomplishes the principal object of the invention. On the other hand, it also will be obvious to those skilled in the art that the illustrated embodiments of the invention may be vari ously changed and modified, or features thereof, singly or collectively, embodied in other combinations than those illustrated, without departing from the spirit of the invention, or sacrificing all of the advantages thereof, and that accordingly, the disclosure herein is illustrative only, and the invention is not limited thereto.

I claim:

1. An electric heater grid comprisinga-unitary woven fabric having a'transverse first portion intermediate a second portion and a third portion, said first portion having warp elements and weft elements both of yarn of insulating material, said second and third portions having warp elements common with those of said first portion, and said second and third portions each having two spaced collaterally running weft elements each comprising electric resistance wire, said weft elements of said second portion being respectively continuous with said weft elements of said third portion, one of the weft elements of said second portion being joined to one of the weft elements of said third portion along one selvedge of said first portion, and the other weft element of said second portion being joined to the other weft eleand arranged to produce an effect varying'with the temperature at said place; and indicating means responsive to said effect and constructed and arranged to indicate the temperature at said upper surface.

3. An electric heater grid comprising a unitary woven fabric having a transverse first portionin termediate a second portion and a third portion, said first portion having warp elements and weft elements both of yarn of insulating material,

said second and third portions having warp elements common with those of said first portion, and said second and third portions each having two spaced collaterally running weft elements each comprising electric resistance wire, the collaterally running weft elements of said second portion progressing from terminal ends at the free end of said second portion in a direction toward the free end of said third portion, the collaterally running elements of said third portion progressing in said direction to terminals at the free end of said third portion, and said weft elements of said third portion being respectively continuous with said weft elements of said second portion, one of the weft elements of said second portion being joined to one of the weft elements of said third portion along one selvedge of said first portion, and the other weft element of said second portion being joined to the other weft element of said third portion along the other selvedge of said transverse portion.

4. An electric heater grid comprising a unitary woven fabric having a, transverse first portion intermediate a second portion and a third portion, said first portion having warp elements and weft elements both of yarn of insulating material, said second and third portions having warp elements common with those of said first portion, said second and third portions having weft elements comprising electric resistance wire; lead conductor means, for carrying electric current to said electric resistance wires, disposed along a selvidge portion of said fabric and extending from a terminal at the free end of said third portion to the free end of said second portion and there 'electrically. connected to a weft element of said .second portion; said lead conductor means having a loop portion extending laterally therefrom, over said first portion; and thermoresponsive electric switch means disposed at said first portion and interposed in said loop portion of said lead conductor means.

5. An electric heater grid comprising a unitary woven fabric having a transverse first portion intermediate a second portion and a third portion, said first portion having warp elements and weft elements both of yarn of insulating material, said second and third portions having warp elements common with those of said first portion, and said second and third portions each having two spaced collaterally running weft elements each comprising electric resistance wire, the collaterally running weft elements of said second portion progressing from terminal ends at the free end of said second portion in a direction toward the free end of said third portion, and the collaterally running elements of said third pore tion progressing in said direction to terminal ends I at the free end of said third portion; lead conductor means, for carrying electriccurrent to said electric resistance wires, disposed along a selvedge portion of said fabric and extending from a terminal at the free end of said third portion to the free end of said second portion and there electrically connected to both of the weft elements of said second portion; said lead conductor having a loop portion extending laterally therefrom, over said first portion; and thermoresponsive electric switch means disposed at said first portion and.

interposed in said loop portion of said lead conductor means.

6. An electric heater made from a continuously woven fabric, the fabric including warp elements and weft elements of insulating material, and weft elements of electric resistance wire progressing continuously in the same directionin REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 718,896 Ames et a1 Jan. 20, 1903 723,797 Williams Mar. 24, 1903 1,031,204 Schniewindt July 2, 1912 Number 10 Name Date Jahr Aug. 27, 1912 Rohne Feb. 15, 1921 Negromanti May 24, 1921 Craddick et a1 May 22, 1923 Lackland Jan. 10, 1928 Graham Dec, 24, 1929 Dlmbar Dec. 15, 1931 Burkholder Aug. 8, 1933 De Laney et al Oct. 22, 1935 Hall Dec. 24, 1935 Pecker Nov. 29, 1938 Kidwell June 13, 1939 Van Dam et al. Aug. 5, 1941 Teague et a1 July 7, 1942 Stranszky Oct. 6, 1942 

